How is location accuracy measured in Android?
Does anyone know the proper interpretation of the accuracy measurements returned by getAccuracy()? For instance, are they calculated as:
Circular Error Probability (meaning, if i understand correctly, radius of a 50% confidence circle)?
Radius of 95% confidence circle?
something else?
In addition, what are the actual calculations that are used and how much can we rely on them? Does it depend on the source of the location estimate (GPS vs. network)?
Many thanks for any advice you can give me.
Answer
To answer one part of the question, the number is the radius of 68% confidence, meaning that there is a 68% chance that the true location is within that radius of the measured point in meters. Assuming that errors are normally distributed (which, as the docs say, is not necessarily true), that means that this is one standard deviation. For example, if Location.getAccuracy returns 10, then there's a 68% chance the true location of the device is within 10 meters of the reported coordinates.
http://developer.android.com/reference/android/location/Location.html#getAccuracy()